Randomised double-blind clinical trial of intermediate- versus high-dose chloral hydrate for neuroimaging of children.

Orally administered chloral hydrate is the most widely used sedative in children undergoing MRI. We compared intermediate- and high-dose oral chloral hydrate in 97 consecutive children undergoing MRI in a prospective, controlled, double-blind, randomised clinical trial. There were 50 girls and 47 boys, mean weight (+/- SD) 14.7 +/- 6.4 kg, and mean age 38 +/- 31. The children were randomly allocated to receive chloral hydrate syrup either 70 mg/kg (group A, n = 50) or 100 mg/kg (group B, n = 47). These two groups were not significantly different in sex, weight, age, diagnosis or ambulatory medication. The mean initial dose (+/- SEM) was 64 +/- 2 mg/kg for group A and 93 +/- 2 mg/kg for group B. Because adequate sedation was not achieved, 14 patients in group A and 6 in group B required a second dose, giving a mean total dose of 70 +/- 2 mg/kg for group A and 96 +/- 2 mg/kg for group B. The percentage of successful examinations after the initial dose (A: 64%, B: 87%; p < 0.05) and the total dose (A: 92%, B:100%; p = 0.14) was higher in group B. Significant differences were found for the time of onset of sedation (A:28 +/- 2 min, B: 21 +/- 1 min; p < 0.05), but not for the time to spontaneous awakening after the completion of the examination. The rate of adverse reactions was similar (A: 20%, B: 21%; p = 1.00). We conclude that high-dose oral chloral hydrate improves the management of children undergoing MRI.